506 research outputs found
Revisiting property transfer theory: English law and Chinese law compared
The relationship between a conveyanceâs validity and its underlying contract has been a classic but unsettled topic for comparative private lawyers over the past three decades. This paper attempts to add positivist and normative observations drawn from property transfer theories and practices in English and Chinese law. A jurisdiction adopting an âintent plusâ model does not necessarily recognise a separate intent to convey distinct from the intent in the underlying contract, as exemplified by Chinese law, while a jurisdiction adopting the âintent aloneâ model does not necessarily deny the separate intent to convey, as exemplified by English law. One advantage for a jurisdiction that takes the separatist approach is its flexibility, so that it can still choose between pure causality, pure abstraction, or context-based abstraction at a later stage. Recent developments show that English and Chinese law are moving towards this approach. As to whether flaws in the underlying contract infect the validity of the conveyance, the English position depends on vitiating factors, whereas the mainstream Chinese judgments tend to be pro-causal. Justifications favouring causality provided in the English and Chinese academia are different, though neither can stand up to scrutiny. The detecting opportunity argument submitted in this paper helps to justify abstraction
Bound Controller for a Quadruped Robot using Pre-Fitting Deep Reinforcement Learning
The bound gait is an important gait in quadruped robot locomotion. It can be
used to cross obstacles and often serves as transition mode between trot and
gallop. However, because of the complexity of the models, the bound gait built
by the conventional control method is often unnatural and slow to compute. In
the present work, we introduce a method to achieve the bound gait based on
model-free pre-fit deep reinforcement learning (PF-DRL). We first constructed a
net with the same structure as an actor net in the PPO2 and pre-fit it using
the data collected from a robot using conventional model-based controller.
Next, the trained weights are transferred into the PPO2 and be optimized
further. Moreover, target on the symmetrical and periodic characteristic during
bounding, we designed a reward function based on contact points. We also used
feature engineering to improve the input features of the DRL model and improve
performance on flat ground. Finally, we trained the bound controller in
simulation and successfully deployed it on the Jueying Mini robot. It performs
better than the conventional method with higher computational efficiency and
more stable center-of-mass height in our experiments.Comment: 7page
Pressure-induced one-dimensional oxygen ion diffusion channel in lead-apatite
Recently, Lee et al. claimed that the experimental observation of
room-temperature ambient-pressure superconductivity in a Cu-doped lead-apatite
(Pb10-xCux(PO4)6O). The study revealed the Cu doping induces a chemical
pressure, resulting in a structural contraction of one-dimensional Cu-O-Cu
atomic column. This unique structure promotes a one-dimensional electronic
conduction channel along the c-axis mediated by the O atoms, which may be
related to superconductivity. These O atoms occupy 1/4 of the equivalent
positions along the c-axis and exhibit a low diffusion activation energy of 0.8
eV, indicating the possibility of diffusion between these equivalent positions.
Here, using machine-learning based deep potential, we predict the
pressure-induced fast diffusion of 1/4-occupied O atoms along the
one-dimensional channel in Pb10(PO4)6O at 500 K, while the frameworks of Pb
triangles and PO4 tetrahedrons remain stable. The calculation results also
indicate Cu doping can provide appropriate effective chemical pressure,
indicating the one-dimensional ion diffusion channel may appear in
Pb9Cu(PO4)6O, even at ambient pressure. Our finding shows that the
one-dimensional ions diffusion channel may be an important factor to affects
the fabrication and electrical measurement of doped lead-apatite.Comment: 15 pages, 7 figure
Mid-frequency prediction of transmission loss using a novel hybrid deterministic and statistical method
A novel hybrid deterministic-statistical approach named ES-FE-SEA method specially used to predict the sound Transmission loss of panels in mid-frequency is proposed in this paper. The proposed hybrid methods takes the best advantages of edged-based smoothing FEM (ES-FEM) and statistical energy analysis (SEA) to further improve the accuracy of mid-frequency transmission loss predictions. The application of ES-FEM will âsoftenâ the well-known âoverly-stiffâ behavior in the standard FEM solution and reduce the inherent numerical dispersion error. While the SEA approach will deal with the physical uncertainty in the relatively higher frequency range. Two different types of subsystems will be coupled based on âreciprocity relationshipâ theorem. The proposed was firstly applied to a standard simple numerical example, and excellent agreement with reference results was achieved. Thus the method is then applied to a more complicated model-a 2D dash panel in a car. The proposed ES-FE-SEA is verified by various numerical examples
Anisotropic Interfacial Force Field for Interfaces of Water with Hexagonal Boron Nitride
This study introduces an anisotropic interfacial potential that provides an
accurate description of the van der Waals (vdW) interactions between water and
hexagonal boron nitride (h-BN) at their interface. Benchmarked against the
strongly constrained and appropriately normed (SCAN) functional, the developed
force field demonstrates remarkable consistency with reference data sets,
including binding energy curves and sliding potential energy surfaces for
various configurations involving a water molecule adsorbed atop the h-BN
surface. These findings highlight the significant improvement achieved by the
developed force field in empirically describing the anisotropic vdW
interactions of the water/h-BN heterointerfaces. Utilizing this anisotropic
force field, molecular dynamics simulations demonstrate that atomically-flat
pristine h-BN exhibits inherent hydrophobicity. However, when atomic-step
surface roughness is introduced, the wettability of h-BN undergoes a
significant change, leading to a hydrophilic nature. The calculated water
contact angle (WCA) for the roughened h-BN surface is approximately 64{\deg},
which closely aligns with experimental WCA values ranging from 52{\deg} to
67{\deg}. These findings indicate the high probability of the presence of
atomic steps on the surfaces of experimental h-BN samples, emphasizing the need
for further experimental verification. The development of the anisotropic
interfacial force field for accurately describing interactions at the
water/h-BN heterointerfaces is a significant advancement in accurately
simulating the wettability of two-dimensional (2D) materials, offering a
reliable tool for studying the dynamic and transport properties of water at
these interfaces, with implications for materials science and nanotechnology.Comment: 22 pages, 5 figure
Cell Biomechanical Modeling Based on Membrane Theory with Considering Speed Effect of Microinjection
As an effective method to deliver external materials into biological cells,
microinjection has been widely applied in the biomedical field. However, the
cognition of cell mechanical property is still inadequate, which greatly limits
the efficiency and success rate of injection. Thus, a new rate-dependent
mechanical model based on membrane theory is proposed for the first time. In
this model, an analytical equilibrium equation between the injection force and
cell deformation is established by considering the speed effect of
microinjection. Different from the traditional membrane-theory-based model, the
elastic coefficient of the constitutive material in the proposed model is
modified as a function of the injection velocity and acceleration, effectively
simulating the influence of speeds on the mechanical responses and providing a
more generalized and practical model. Using this model, other mechanical
responses at different speeds can be also accurately predicted, including the
distribution of membrane tension and stress and the deformed shape. To verify
the validity of the model, numerical simulations and experiments are carried
out. The results show that the proposed model can match the real mechanical
responses well at different injection speeds.Comment: 10 pages, 12 figures, submitted to IEEE TMech
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